1. Field of the Invention
The present invention relates to a Code Division Multiple Access (hereinafter, referred to as CDMA) mobile telecommunication system and, in particular, to a switching apparatus and method for switching over to a spare transceiver for maintenance and repair of a troubled transceiver when the transceiver, preferably, but not exclusively, for use in a CDMA cellular base station, gets into trouble.
2. Description of the Related Art
Generally, a CDMA mobile telecommunication system is provided with a low power radio transmitter and receiver (transceiver) and a control unit in a central area of each service area, i.e., a cell, in which a cellular base station serves as a relay to communicate by radio with a selected mobile telephone terminal equipment. A receiving frequency applied from each mobile terminal equipment is converted and amplified into a much lower radio frequency, which is often referred to as an "intermediate frequency". The cellular base station converts the receiving frequency to the intermediate frequency, which is subsequently converted to a transmit intermediate frequency on basis of a tuning frequency of each transceiver.
A cellular base station of CDMA mobile telecommunication system has a multiplicity of transceivers adapted to convert an intermediate frequency to and from the respective different radio frequencies corresponding to each mobile terminal equipment, in which system the number of those transceiver depends upon the number of radio channels. When the system needs to perform maintenance and repair of a transceiver due to any one of the transceivers operating in a CDMA cellular base station getting into trouble or malfunctioning, one of a plurality of switches, each switch corresponding to a respective transceiver, i.e., the switch coupled to the troubled transceiver, is turned off to switch over to a predetermined spare transceiver that continues the conversion of the intermediate frequency instead of the troubled transceiver.
Thus, a problem of space occurs because of such a large number of switches in use which require a lot of control cables connected with those switches, and which inevitably leads to complicated construction of the transceiver system and higher cost.